Baker&#39;s oven



March 3, 1936. c, T. HATCH 2,032,751

BAKER S OVEN Filed Nov. 2, 1934 5 Sheets-Sheet l INVENTOR B) I -6 K g( 76 9 A TTORNE Y5 arch 9 6- c. T. HATCH 2,@32,751

BAKERS'OVEN Filed Nov. 2 1954 5 Sheets-Sheet 2 4 9% 'Q Q 5 a a 1g STOPTART MAGNETIC SWITCH ATTORNEY$ March3,1936. C. 1-. HATCH 32551 BAKERSOVEN Filed Nov. 2 1934 3 Sheets-Sheet 5 INVENTOR mar/as 77 f/afch 6 pzwzw ATTORNEYs Patented Mar. 3, 1936 PATENT OFFICE BAKER/S OVEN Charles T.Hatch, Albion, Mich., assignor to Union Steel Products Company, Albion,Mich.

Application November 2, 1934, Serial No. 751,114

25 Claims.

v This invention relates to bakers ovens of the type employing a reel orconveyor having a series of suspended shelves for carrying the goods inthe oven, the shelves being maintained in equilibrium mainly by gravity.

Heretofore, in bakers ovens of this character, there is present thepossibility of damage to the load or to the oven in the event of theload not being properly placed upon the shelves and jamming between theshelves and Walls and load or between the shelves and/or load as theypass each other at the top and bottom of the conveyor. It is possiblefor a serious accident to occur in the event that the operator does not;place the pans properly upon the shelves or properly load the shelves.I have observed that Whenever this has occurred it has been almostimpossible to definitely fix the responsibility due to the fact that theaccident itself destroyed all evidence as to exactly what caused it.

The main object of my invention is to provide automatic means in abakers oven of this character for minimizing the possibility of anaccident of this nature due to the pans jamming be- 7 tween the shelvesor between the oven parts and the shelves.-

I Another object of my invention is to provide a conveyor having itsshelves stabilized sufficiently to enable the baker to load them withoutundue i swaying of the shelves and yet at the same time in the claims.

A structure which is a preferred embodiment of my invention isillustrated in the accompanying drawings, in which:

Fig. 1 is a fragmentary view in front elevation of a bakers ovenembodying the features of my invention.

Fig. 2 is an enlarged transverse vertical section on. a linecorresponding to line 22 of Fig. 1.'

Fig. 3 is an enlarged fragmentary perspective view of the conveyor.

" Fig. 4 is an enlarged fragmentary detail section on a linecorresponding to line 44 of Fig. 2. Fig. 5 is a fragmentary endelevation of the conveyor, the dotted lines showing how the severalshelves tilt in unison.

Fig. 6 is a simplified diagrammatic representation of the control means.

In the embodiment of my invention illustrated in the drawings, numeral lin general indicates a bakers oven having a substantially circularcasing 2 provided with vertical end walls 3, 3. The casing is heatinsulated as shown by Fig. 2 and is provided with a longitudinal dooropening 4 having a pair of longitudinally alined doors 5, 5 hinged tothe rod 6 at the bottom of the door opening. A gas burner 1 is arrangedin the bottom 8 of the oven, there being a flame deflecting plate 9mounted above the burner.

The ends of the conveyor shaft ID are journaled upon the end walls 3, 3,the shaft being driven by the conveyor driving motor I I throughsuitable gears. The end frames or annular spiders l2 of the conveyor arefixed to the shaft H3 in spaced relation for rotation therewith and areprovided with radial-supports or brackets I3 for the pan shelves I4. Theshelves are provided with hangers at their ends pivotally swung betweenthe supports l3 so that they are maintained by gravity in asubstantially horizontal position throughout their travel with therotary conveyor.

The journals I5 of the shelves at one end of the conveyor have dependingarms l6 connected thereto and adapted to tilt or swing with the shelves.The lower or outer ends of the armslB are connected by means of a seriesof links ll, the ends of the links being connected to the arms bylateral pivot pins l8 each having an enlarged contact head Iii-see Fig.4. The arm or lever link assembly of the shelves is such that when oneshelf is tilted the other shelves are tilted correspondingly asillustrated by Fig. 5. However, the shelves are stabilized sufficientlyby this assembly to enable the baker to load them without undue swayingof the shelves and yet at the same time they are free enough so that noundue friction is set up which would cause an excessive vibration whenthe oven is in operation.

On the inner side of one of the end walls of the casing, I mount a pairof curved resilient contact strips or bars 20 and 2| at opposite sidesof the normal path of the heads I9 and normally spaced therefrom toprovide therewith a normally open control switch, the strips beingpositioned adjacent the door opening 4 and extending above and below thesame as shown by Fig. 2. The contact strips or contact bars 20 and 2|are preferably made of chromium plated spring steel and are supportedonly at their ends by means of supterrupts the control circuit operatingthe conveyor driving motor II and other apparatus to shut down theoperation of the oven. This shut-down occurs before any damage hasbeendone either to the material being baked or to the oven itself.

The fact that the shelves are caused to swing in unison makes itpossible for me to use comparatively short contact bars or strips, itbeing only necessary to make these bars long enough to insure .atleastone shelf being between the bars at all times. Consequently, regardlessof the positioninthe oven at which the obstruction may occur,.the effectis transmitted to the shelf Whose equalizer pin head is between thecontact bars, and assoon as the angle of inclination is 10 either: oneway or the other from the horizontal, contactis madeand the operation ofthe oven immediately stopped.

The drive between the motor II and the conveyor shaft- II] is providedwith a friction clutch (not shown) which is very easily disengaged bypulling the shaft'23 on which the-hand crank 24 is located out towardthe front of the oven to engage the hand driving gears (not shown). Afew-revolutions of the hand crank will back up the conveyor suflicientlyto release the-pans which have-become caught so that the baker can pushthem back into their proper position on the shelf by means of a stick orpeel, thus enabling him to get the oven back into its normal operationwithin a very short time after the stoppage has 7 occurred.

Byreference to Fig. 6, it will'be observed that the-contact heads I!)are connected to ground 25.

The manually operated switch 26 is arranged in thesupply circuit 21 inadvance of the transformer '28, the secondary of which supplies thecontrol circuit with current at'substantially 24 volts. The-coil winding29 of the relay 30 is connected-to the control circuit in such mannerthat when the manually operated switch 26 is closed, the relay is closedand the control circuit is put in operative condition. The double actingrelay 3| is connected to the control circuit so as to be controlled bythe, control switch consisting of the contact heads l9 and contactstrips 20 and 2|; the; arrangement being such that when the controlswitch is closed the coil winding 32 or therelay 3| is energized to openthe circuit including the relay winding 33 of the conveyor driving motorswitch 34, and at the same time establish the circuit to the bell 35 orother alarm.

A holding circuit is also established through the winding 33 to keep thebell ringing until the trouble is corrected. The coil windings 3B and 31of the blower driving motor switch 38 and gas valve 39 are arranged inseries circuit relation with the circuit including the relay winding 33and thenormallyclosed manually opened stop switch 40.

' The blower motor 4| is conneected to the sup- 'plycircuit 21 sothatunder normal conditions it operates when the manually closed switch26 and the relay 38 are closed. The blower motor 4| operates a blower 42in conjunction with the gas supply for delivering a proper mixture ofgas and air to the burner 1. The starting switch 43 for the conveyordriving motor II is connected to the relay coil 33 so as to energize thelatter when the switch is momentarily closed. The energization of thecoil 33 closes the contacts of the switch 34 and the contacts of theholding switch 44, the latter being in series with the stop switch,

Briefly, in operation the manually controlled switch 26 is closed first.This switch must be closed in order to put the oven in operation. On theclosing of the switch 26, the relay automatically operates to place thecontrol circuit 3| in operative condition so that when the startingswitch 43 is momentarily closed, the coil winding 33 is energizedresulting in the operation of the conveyor driving motor Theenergization of the coil 33 also closes the holding switch 44. Theclosing of the switch 26 results in the operation ofv the blower motor4| and the opening, of the gas valve .39.

As. long as the contact heads |9 follow their normal path between thecontactstrips 20 and 2| without touching the, latter, the deviceoperates in a normal manner. However, if the shelves should incline morethan the predetermined degree from the horizontal, theheads l9 willstrike one or the other of the contact strips. When this occurs, therelay 3| is operated, opening the circuitincluding the coilsv of relays34, 36 and 31, thereby stopping the blower motor 4|, closing'the gasvalve 39 andstopping the conveyor driving motor The oven is completelyshut down before, any damage has been done either to the material beingbaked or to the oven itself. At the same time that the control circuitis broken, the circuit leading to the electric gong 35 is closed and thebell rings, giving the signal to the operator that something is wrongwith the oven. Thebell will continue to ring until the manuallycontrolled switch 26 is opened. v By investigation, the baker canusually determine just what is causing the difficulty and can back theconveyor up by hand, straighten out the pans which are out of place andstart the oven in the usual manner.- There are no safety pins to replacenor any electrical equipment to reset. My safety device is-automaticallyplaced on guard for the detection of future trouble of the same nature.

To make certain that the oven cannot be operated without the safetydevice being in operation, I provide the relay 36 through which thecontrol circuit current must flow. This relay is actuated by current inthe secondary circuit'of the transformer 28 which furnishes currenttothe contact bars inside of the oven. In the event oftrans-.

former failure or should the operator forget to throw the line switch 28supplying the primary current to the transformer, thisrelay 33 willremainopen and it will be impossible to startthe oven until electriccurrent. is supplied to the contact strips inside of the oven.Consequently, it is impossible to operate the-oven without the safetydevice being on duty to guard against a possiblev accident. 7

While .I have described my improvements in connection with a bakers ovenhaving a conveyor of the rotary type, it will be appreciated by thoseskilled in the art that the invention is applicable vice embodying thefeatures of my invention is extremely desirable on an oven of this type.

In addition to the gong or hell that I use for signaling trouble, othersignals such as colored lights can be used with the apparatus.

I have illustrated and described my improvements in an embodiment whichI have found very practical. I have not attempted to illustrate ordescribe other embodiments or adaptations, as it is believed thisdisclosure will enable those skilled in the art to embody or adapt myimprovements as may be desired.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a bakersoven, the combination of a casing having a door opening atthe front, a conveyor having annular end members spaced from the endwalls of the casing, a series of longitudinal pan shelves pivotallysuspended between said conveyor end members, lever arms connected to thepivots of said shelves at one end of said conveyor, laterally projectingpins on the ends of said arms and having contact heads movable out oftheir normal path by the tilting of the shelves, links connecting saidpins for uniform tilting movement when one shelf is tilted, a pair ofcurved resilient contact strips mounted on the inner side of one of saidend walls at opposite sides of the normal path of said heads andnormally spaced therefrom to provide therewith a normally open controlswitch, the strips being positioned adjacent the door opening andextending above and below the same, and a control circuit including saidswitch for shutting down the oven when the shelves are tiltedsufficiently to cause one of said heads to engage one of said strips andclose said switch.

2. In a bakers oven, the combination of a substantially circular casinghaving vertical end walls and a longitudinal door opening at the front,a rotary conveyor journaled upon said end walls and having end membersspaced therefrom, a series of longitudinal shelves pivotally suspendedbetween said end members, lever arms connected to the pivots of saidshelves at one end of said conveyor, laterally projecting pins on saidarms and having contacts movable out of their normal path by the tiltingof the shelves, means connecting said shelves for uniform tiltingmovement when one shelf is tilted, a pair of curved contact stripsmounted on the inner side of one of said end walls at opposite sides ofthe normal path of said contacts and normally spaced therefrom, thestrips being positioned adjacent the door opening and extending aboveand below the same, and control means for shutting down the oven whenthe shelves are tilted sufliciently to cause one of said contacts toengage one of said strips.

3. In a bakers oven, the combination of a casing, a conveyor having endmembers, a series of longitudinal shelves pivotally suspended betweensaid end members, lever arms connected to said shelves at one end ofsaid conveyor, laterally projecting pins on said arms and havingcontacts movable out of their normal path by the tilting of the shelves,means connecting said shelves for uniform tilting movement when oneshelf is tilted, a pair of curved contact strips mounted at oppositesides of the normal path of said contacts and normally spaced therefrom,and control means for shutting down the oven when the shelves are tiltedsufficiently to cause one of said contacts to engage one of saidvstrips.

4. The combination with a housing provided with a door opening at thefront thereof, a rotary conveyor within said housing, driving means forsaid conveyor, an annular series of uniformly spaced shelves pivotallymounted on said conveyor, an arm connected to each shelf so that theswinging movement of the shelf is imparted to the arm, connecting linksfor the arms whereby the swinging movement of one shelf is imparted toall of them and forces tending to tilt one shelf are resisted by all ofthem, a control means for said driving means including a contact elementcarried by each of said arms and traveling in a circular path when theshelves are in normal untilted position, and a pair of coactingrelatively fixed contact bars disposed in opposed spaced relation onopposite sides of the normal path of the contact elements carried bysaid arms to be engaged thereby when a shelf is tilted more than apredetermined degree, the fixed contact bars being positioned to beoperatively associated with the contact elements of the shelves inoperative relation to the door opening and being of a length at leastequal to the spacing of the shelves so that there is always a contactbar of one of the shelves in operative relation thereto.

5. The combination with a rotary conveyor, driving means for saidconveyor, an annular series of uniformly spaced shelves pivotallymounted on said conveyor, an arm connected to each shelf so that theswinging movement of the shelf is imparted to the arm, connecting linksfor the arms whereby the swinging movement of one shelf is imparted toall of them and forces tending to tilt one shelf are resisted by all ofthem, a control means for said driving means including a contact elementcarried by each of said arms and traveling in a circular path when theshelves are in normal untilted position, and a pair of coactingrelatively fixed contact bars disposed in opposed spaced relation onopposite sides of the normal path of the contact elements carried bysaid arms to be engaged thereby when a shelf is tilted more than apredetermined degree.

6. The combination with a housing provided with a door opening at thefront thereof, an endless conveyor within said housing, driving meansfor said conveyor, an annular series of uniformly spaced shelvespivotally mounted on said conveyor, an arm connected to each shelf sothat the swinging movement of the shelf is imparted to the arm,connecting links for the arms whereby the swinging movement of one shelfis imparted to all of them, a control means for said driving meansincluding a contact element carried by each of said arms and travelingin a predetermined path when the shelves are in normal position, and apair of coacting relatively fixed contact bars disposed in opposedspaced relation and on opposite sides of the normal path of the contactelements carried by said arms to be engaged thereby when they departmore than a predetermined degree from their normal path, the fixedcontact bars being positioned to be operatively associated with thecontact elements of the shelves in operative relation to the dooropening and being of a length at least equal to the spacing of theshelves so that there is always a contact bar of one of the shelves inoperative relation thereto.

7. The combination with a housing provided with a door opening at thefront thereof, an endless conveyor within said housing, driving meansfor said conveyor, an annular series of uniformly spaced shelvespivotally mounted on said conveyor, an arm connected to each shelf sothatthe swinging movement of the shelf is imparted to the arm,connecting links for the arms whereby the swinging movement of one shelfis imparted to all of them, a control means for said driving meansincluding a contact element carried by each of said arms and travelingin a predetermined path when the. shelves are in normal position, and acoacting relatively fixed contact member disposed at the side of thenormal path of the contact elements carried by said arms to be engagedthereby when they depart more than a predetermined degree from theirnormal path, the fixed contact member being positioned to be operativelyassociated with the contact elements of the shelves in operativerelation to the door opening and being of a length at least equal to thespacing of the shelves so that there is always a contact member of oneof the shelves in operative relation thereto.

8. The combination with an endless conveyor, driving means for saidconveyor, a series of spaced shelves pivotally mounted on said conveyor,an arm connected to each shelf so that the swinging movement of theshelf is imparted to the arm, connecting links for the arms whereby theswinging movement of one shelf is imparted to all of them, a controlmeans for said driving means including a circuit control element carriedby each of said arms and traveling in a predetermined path when theshelves are in normal position, and a pair of coacting relatively fixedcircuit control means disposed in opposed spaced relation and onopposite sides of the normal path of the circuit control elementscarried by said arms to be contacted thereby when they depart more thana predetermined degree from their normal path.

9. In an oven, the combination of a conveyor, a series of shelvespivotally suspended on said conveyor, a series of laterally projectingpins terminating in contacts at their outer ends adapted to tilt withsaid shelves, a series of links pivoted at their ends to said pins andconnecting them for uniform tilting, a pair of contact strips disposedat opposite sides of the path of said contacts and spaced therefrom tobe normally out of contact therewith, the tilting of any one of saidshelves acting to tilt all of said levers and bring one of said contactsinto contact with one of said strips, and control means including saidcontacts and strips for shutting down the oven when such contact isestablished.

10. In an oven, the combination of a conveyor, a series of shelvespivotally suspended on said conveyor, a series of laterally projectingpins terminating in contacts at their outer ends adapted to tilt withsaid shelves, a pair of contact strips disposed at opposite sides of thepath of said contacts and spaced therefrom to be normally out of contacttherewith, and control means including said contacts and strips forshutting down the oven when such contact is established.

11. The combination of a conveyor, a series of shelves pivotallysupported thereon, a series of depending levers connected to saidshelves at their pivots at one end of the conveyor and having laterallyprojecting pins terminating in contacts at their outer ends, a series oflinks pivoted at their ends to said pins and connecting said levers foruniform tilting, and control means including said contacts for shuttingdown the oven when said shelves are tilted a predetermined degree out oftheir normal path.

12. The combination of a conveyor, a series of shelves pivotallysupported thereon. a series of depending levers connected tosaid'shelves at their pivots atone end of the conveyor and'havinglaterally projecting pins, a series of links pivoted at their ends tosaid pins and connecting said levers for uniform tilting, and controlmeans for shutting down the oven when said shelves are tilted apredetermined degree out of their normal path.

13.-The combination of an endless conveyor having a series of spacedpivotally hung shelves normally maintaining a horizontal position bygravity, depending end levers connected to said shelves at their axes, aseries of connecting links pivotally connected at their ends to theouter ends of said levers for keeping said shelves in the same relativehorizontal position, and control means for stopping said conveyor whensaid shelves are tilted more than a predetermined degree from thehorizontal.

14. The combination of an endless conveyor having a series of spacedpivotally hung shelves normally maintaining a horizontal position bygravity, a series of connecting links for keeping said shelves in thesame relative horizontal position, and control means for stopping saidconveyor when said shelves are tilted more than a. predetermined degreefrom the horizontal.

15. The combination of an endless conveyor having a series of spacedpivotally suspended shelves normally maintaining a horizontal positionby gravity, connecting means for said shelves whereby they are kept inthe same relative horizontal position, and a control means for stoppingsaid conveyor when one of said shelves is tilted more than apredetermined degree from the horizontal.

16. In a bakers oven, the combination with a conveyor having a series ofpan shelves and a driving motor, heating means including a gas supplyhaving a valve, and a blower having a driving motor, of automaticcontrol means for stopping said blower and conveyor and closing said gasvalve when said shelves tip more than a predetermined degree, said meansincluding arms adapted to tip with said shelves and having lateralcontacts, a pair of spaced stationary contact strips arranged atopposite sides of the normal path of said contacts and spaced therefromto provide therewith a normally open control switch, and control circuitmeans acting to close said gas valve and stop said blower and conveyormotors on the closing of said control switch and adapted to control theoperation of said conveyor motor so that the latter cannot be operatedunless the control circuit means is in operative condition.

17. In a bakers oven, the combination with a conveyor having a series ofpan shelves, heating means including a gas supply having a valve, and ablower, of automatic control means for stopping said blower and conveyorand closing said gas valve when said shelves tip more than apredetermined degree, said means including arms adapted to tip with saidshelves and having lateral contacts, a pair of spaced stationary contactstrips arranged at opposite sides of the normal path of said contactsand spaced therefrom to provide therewith a normally open controlswitch, and control circuit means acting to close said gas valve andstop said blower and conveyor on the closing of said control switch andadapted to control the operation of said conveyor so that the lattercannot be operated unless the control circuit means is in operativecondition.

18. In an oven, the combination witha conveyor having a series ofshelves and a driving motor, heating means including a gas supply havinga valve, and a blower having a driving motor, of automatic control meansfor stopping said blower and conveyor and closing said gas valve whensaidshelves tip more than a predetermined degree, said means including acontrol circuit acting to close said gas valve and stop said blower andconveyor motors on the closing of said control switch and adapted tocontrol the operation of said conveyor motor so that the latter cannotbe operated unless the control circuit is in operative condition.

19. In an oven, the combination with a conveyor having a series ofshelves, heating means including a gas supply having a valve, and ablower, of automatic control means for stopping said blower and conveyorand closing said gas valve when said shelves tip more than apredetermined degree.

20. The combination in an oven, of heating means, an endless conveyorcomprising a series of pivotally suspended shelves, driving means forsaid conveyor, connecting means for said shelves whereby the swingingmovement of one shelf on its pivot is imparted to all of them, and acontrol means for said heating means and driving means comprising acontact member operatively associated with each shelf and normallytraveling in a predetermined path but deflected from said path by themovement of its corresponding shelf on its pivot, and a pair of opposedrelatively fixed contact members disposed on opposite sides of thenormal path of said shelf contact members to be engaged thereby when theshelf contact members are diverted from their normal paths by theswinging of a shelf on its pivot beyond a predetermined degree, thefixed contact members being of such length that there is a shelf contactmember associated therewith and so as to be in operative relation to thecontact member of the shelf in loading position.

21. The combination in an oven, of heating means, an endless conveyorcomprising a series of pivotally suspended shelves, driving means forsaid conveyor, connecting means for said shelves whereby the swingingmovement of one shelf on its pivot is imparted to all of them, and acontrol means for said heating means and driving means comprising acircuit control member operatively associated with each shelf andnormally traveling in a predetermined path but deflected from said pathby the movement of its corresponding shelf on its pivot, and arelatively fixed circuit control means disposed at the side of thenormal path of said shelf members to be contacted thereby when the shelfmembers are diverted from their normal paths by the swinging of a shelfon its pivot beyond a predetermined degree, the fixed circuit controlmeans being of such length that there is a shelf member associatedtherewith and so as to be in operative relation to the member of theshelf in loading position,

22. The combination in an oven, of heating means, an endless conveyorcomprising a series of pivotally suspended shelves, driving means forsaid conveyor, connecting means for said shelves one shelf on its pivotis tact members to be engaged thereby when the shelf contact members arediverted from their normal paths by the swinging of a shelf on its pivotbeyond a predetermined degree.

23. The combination in an oven, of heating means, an endless conveyorcomprising a series of pivotally suspended shelves, driving means forsaid conveyor, connecting means for said shelves whereby the swingingmovement of one shelf on its pivot is imparted to all of them, and acontrol means for said heating means and driving means comprising acircuit control member operatively associated with each shelf andnormally traveling in a predetermined path but deflected from said pathby the movement of its corresponding shelf on its pivot, and, arelatively fixed circuit control means disposed at the side of thenormal path of said shelf circuit control members to be contactedthereby when the shelf circuit control members are diverted from theirnormal paths by the swinging of a shelf on its pivot beyond apredetermined degree.

24. The combination of an endless conveyor comprising a series ofpivotally supported shelves, a driving means for said conveyor,connecting means for said shelves whereby the swinging movement of oneshelf on its pivot is imparted to all of them, and a control means forsaid driving means comprising a contact member operatively associatedwith each shelf and normally traveling in a predetermined path butdeflected from said path by the tilting movement of its correspondingshelf on its pivot, and a relatively fixed contact member disposed atthe side of the normal path of said shelf contact members to be engagedthereby when the shelf contact members are diverted from their normalpaths by the tilting of ashelf on its pivot beyond a predetermineddegree.

25. The combination in an oven, of heating means, an endless conveyorcomprising a series of pivoted shelves, connecting means for saidshelves whereby the swinging movement of imparted to all of them, and acontrol means for said heating means comprising a contact memberoperatively associated with each shelf and normally traveling in apredtermined path but deflected from said path by the tilting movementof its corresponding shelf on its'pivot, and a pair of opposedrelatively fixed contact members disposed on opposite sides of thenormal path of said shelf contact members to be engaged thereby when theshelf contact members are diverted from their normal paths by thetilting of a shelf on its pivot beyond a predetermined degree.

CHARLES T. I-IATCI-I.

